JPH01193056A - Fuel injection rate control device for diesel engine - Google Patents

Abstract

PURPOSE:To suppress sticking of fuel mist to a wall surface of a combustion chamber so as to improve a warming-up performance, in warming-up of a diesel engine by increasing/decreasing the capacity of a variable capacity chamber interconnected to a pressurizing chamber of a fuel injection pump and rapidly changing a fuel injection rate. CONSTITUTION:There are provided a fuel injection pump M2 having a pressurizing chamber for pressurizing a pressure of fuel supplied to a diesel engine M1 and a variable capacity chamber interconnected to the pressurizing chamber and a means M3 for changing the capacity of the variable capacity chamber according to the command from the outside. Further, there are provided a means M1 for judging if the diesel engine M1 is in a warming-up state according to the operating state of the diesel engine M1 and a means M5 for outputting a control command to increase/decrease the capacity of the variable capacity chamber by a predetermined number, per the fuel injecting period of the diesel engine M2, when the diesel engine M2 is judged as a warming-up state by the means M4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection rate control device for a diesel engine that is effective during warm-up.

[Prior Art] Conventionally, a fuel injection pump for a diesel engine has been provided with a variable volume chamber that communicates with a pressurizing chamber installed therein, and fuel is injected by increasing or decreasing the volume of the variable volume chamber using a stacked piezoelectric actuator or the like. Techniques for adjusting the fuel injection rate 5, so-called fuel injection rate control, are known. Examples of such technologies include, for example,
The following are proposed: That is, (1) A piezo stack is inserted into a pressure chamber that communicates with a pressurizing chamber of a fuel injection pump of a diesel engine, and the pressure of the pressure chamber is adjusted according to the voltage applied to the piezo stack, thereby controlling the operation of the diesel engine. ``Fuel injection rate control device for diesel engines'' that controls the fuel injection rate through optimal feedback control according to parameters
18249).

(2) At a predetermined time when the fuel pressure in the pump chamber that pressurizes the fuel of the fuel injection pump exceeds a certain pressure, the volume of the variable volume chamber communicating with the pump chamber is increased by an electrostrictive actuator, and the fuel is increased. ``Fuel injection rate control device for diesel engines'' that lowers the injection rate and performs pilot injection with high control accuracy (Japanese Patent Laid-Open Publication No. 61-25925).

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology realizes fuel injection rate control that is effective in the normal operating state after the diesel engine has started and warmed up. No equal consideration was given to improving performance in Generally, in a warm-up state, the temperature of the wall surface of the combustion chamber of a diesel engine is still low, so it is desirable to promote atomization of the fuel spray injected from the fuel injection pump to make it difficult to adhere to the wall surface.

However, in the conventional technology, since the above considerations are not taken, fuel spray tends to adhere to the wall surface, and the warm-up state cannot be completed quickly.

As mentioned above, if fuel spray adheres to the combustion chamber wall during warm-up, the low temperature makes it difficult for the fuel to evaporate, making it difficult to generate an appropriate air-fuel mixture inside the combustion chamber, resulting in smooth combustion. The continuation of the condition was prevented.

In addition, as mentioned above, it is difficult to achieve smooth combustion when the engine is warmed up, so the exhaust gas contains a relatively large amount of unburned fuel, resulting in white smoke and irritating odors. There were also problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection rate control device for a diesel engine that has a simple configuration and can realize suitable fuel injection that does not deteriorate exhaust characteristics even in a warm-up state.

Structure of the Invention [Means for Solving the Problems] The present invention, which has been made to solve the above problems, includes a pressurizing chamber for increasing the pressure of fuel supplied to the diesel engine M1, and a fuel injection pump M2 having a variable volume chamber communicating with the pressurizing chamber; a volume changing means M3 for changing the volume of the variable volume chamber in accordance with an external command; a warm-up state determining means M4 that determines whether the diesel engine M1 is in a warm-up state based on the warm-up state; and when the warm-up state determining means M4 determines that the diesel engine M1 is in the 111 engine state, the fuel injection control means M5 for outputting a command to increase or decrease the volume of the variable volume chamber a predetermined number of times to the volume changing means M3 every fuel injection period of the pump M2;
The gist of the present invention is a fuel injection rate control device for a diesel engine, which is characterized by comprising: and.

Here, the variable volume chamber of the fuel injection pump M2 may be, for example, installed alongside a pressurizing chamber, or may be, for example, provided so as to communicate with a pipe connecting the pressurizing chamber and the diesel engine. You can leave it there.

The volume changing means M3 changes the volume of the variable volume chamber according to an external command. For example, it can be realized by a piezoelectric actuator that supplies charge from a high voltage power source to stacked piezoelectric elements via a drive circuit to expand and contract them.

Here, the piezoelectric element has the property of causing distortion when an electric charge is applied (so-called inverse piezoelectric effect), for example, P
It may be a ceramic laminate such as ZT, an element made of a polymer piezoelectric material, an element made of quartz, or the like.

The warm-up state determining means M4 determines whether the diesel engine M1 is in a warm-up state based on the operating state of the diesel engine M1. For example, starter signal,
It can be configured to determine whether the diesel engine M1 is in a warm-up state based on the cylinder block wall surface temperature, etc. of the diesel engine M1. Further, the determination can be made based on various quantities that can represent the combustion chamber temperature of the diesel engine M1, such as the starter signal, the cooling water temperature of the diesel engine M1, or the elapsed time since the starter was activated.

The control means M5 means that when the warm-up state determining means M4 determines that the warm-up state is present, the control means M5 issues a command to increase or decrease the volume of the variable volume chamber a predetermined number of times during each fuel injection period of the fuel injection pump M2. It is output to the changing means M3.

For example, when in a warm-up state, it can be configured to output a command to perform multi-stage injection by repeating application and discharge of a high voltage to the piezoelectric element a predetermined number of times from the start to the end of one fuel injection.

The warm-up state determining means M4 and the control means M5 are, for example,
This can be realized using independent discrete logic circuits. In addition, for example, in addition to the well-known CPU, ROM,
It may be configured as a logic operation circuit together with a RAM and other peripheral circuit elements, and may realize both of the above means according to a predetermined processing procedure.

[Function] The fuel injection rate control device for a diesel engine according to the present invention has a first
As illustrated in the figure, when the warm-up state determining means M4 determines that the diesel engine M1 is in the warm-up state based on the operating state of the diesel engine M1, the fuel injection pump M2 is injected every time during the fuel injection period of the fuel injection pump M2. , the fuel injection pump M2
The control means M5 outputs to the volume changing means M3 a command to increase or decrease the volume of the variable volume chamber communicating with the pressurizing chamber a predetermined number of times.

That is, when the diesel engine M1 is warmed up, the volume of the variable volume chamber communicating with the pressurizing chamber of the fuel injection pump M2 is increased or decreased by the volume changing means M3 to rapidly change the injection rate. By injecting this portion at a high injection rate, it is possible to avoid fuel spray from adhering to the wall surface of the combustion chamber of the diesel engine M1, which has not yet been sufficiently warmed up.

Therefore, the fuel injection rate control device for a diesel engine of the present invention works to rapidly increase or decrease the fuel injection rate in a warm-up state during one injection period to promote atomization of the fuel.

The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings. FIG. 2 shows a system configuration of a fuel injection rate control device for a diesel engine, which is an embodiment of the present invention.

As shown in the figure, a fuel injection rate control device 1 for a diesel engine includes a diesel engine 2, a distribution type fuel injection pump 3 that pressurizes and pumps fuel to be supplied to the diesel engine 2, and a fuel injection rate control device 1 for a diesel engine. It is composed of a piezoelectric actuator 4 installed side by side, a drive circuit 5 for driving the piezoelectric actuator 4, a high voltage power supply 6, and an electronic control unit (hereinafter simply referred to as ECU) 7 for controlling these.

In the diesel engine 2, a cylinder 11, a piston 12, and a cylinder head 13 form a combustion chamber 14, and a fuel injection valve 15 is disposed in the combustion chamber 14.

The distribution type fuel injection pump 3 is connected to a drive pulley 2 connected to the crankshaft of the diesel engine 2 by a transmission mechanism such as a belt.
The driving force is transmitted via 1. The drive pulley 21
A vane type pump 23 serving as a fuel feed pump, a pulse gear 24 having a plurality of protrusions carved at equal intervals on the outer circumferential surface, and a coupling 25 are connected to the drive shaft 22 coupled to the drive shaft 22 . The coupling 25 is connected to one end of a plunger 27 that is integrally connected to a cam plate 26, and the other end of the plunger 27 is connected to the cylinder 2.
It is inserted into the interior of the day. The coupling 25 and the plunger 27 rotate together, and the plunger 27 is supported so as to be able to reciprocate in the axial direction indicated by arrows A and B in the figure. Note that the plunger 27 and the cam plate 26 are urged by a spring 29 in the direction shown by arrow A in the figure.

Between the coupling 25 and the cam plate 26,
A roller ring 30 is provided. The roller ring 3
On the surface facing the cam plate 26 of 0, a cam roller 31 is arranged along the circumference around the rotation axis of the roller ring 30.
is installed. A protrusion 26a is provided on the surface of the cam plate 26 facing the roller ring 30. Rotational force is transmitted to the cam plate 26 by the drive shaft 22 via the coupling 25, and the cam plate 26, which is in pressure contact with the roller ring 30, rotates, thereby rotating the plunger 27.
, reciprocates in the direction shown by B to distribute and pressure feed fuel.

A block 33 is attached to the head of the housing 32 of the fuel injection pump 3 by fitting with the cylinder 2. A pressurizing chamber 34 is formed inside the block 33 by the plunger 27 and the cylinder 2. The plunger 27 has fuel introduction recesses 3 formed on the outer peripheral surface corresponding to the number of cylinders and sucking fuel inside the housing 32.
5, and pressurizes the sucked fuel inside the pressurizing chamber 34.

Further, the plunger 27 is recessed in the outer peripheral surface corresponding to the number of cylinders of the diesel engine 20, and includes a distribution boat 36 for distributing the pressurized fuel and a spill boat 37 for overflowing surplus fuel of the pressurized fuel. Equipped with. Furthermore, the spill boat 37 of the plunger 27
A spill ring 38 is slidably fitted around the spill ring 38, which controls the amount of fuel injection by adjusting the timing at which the plunger 27 finishes pressurizing the fuel. The block 33 includes a fuel supply passage 39a communicating with the distribution water port 36;
A delivery valve 40 connected to the fuel supply passage 39a
a is arranged. The delivery valve 40a is connected to the fuel injection valve 15 described above via a fuel pipe 41.

The piezoelectric actuator 4 includes a casing 51, a piston 52 that is fluid-tightly and slidably fitted into a hollow part inside the casing 51, one end of which is in contact with the piston 52, and the other end of which is in contact with the casing 51. It is composed of a piezoelectric element 53 fixed to the lower end surface of the hollow, and a signal line 54 which is a conduction path for charges generated by the piezoelectric element 530 or charges supplied to the piezoelectric element δ3. The piezoelectric actuator 4 is connected to the block 33 of the fuel injection pump 3 by a threaded portion 51a carved on the outer periphery of the distal end of the casing 51, and is connected to the block 33 of the fuel injection pump 3 in the hollow portion of the casing 51, the upper end surface 52a of the piston 52, and the A variable volume chamber 55 is formed from the block 33, and the variable volume chamber 55 communicates with the pressurizing chamber 34 of the fuel injection pump 3 through a communication hole 56. The piezoelectric element 53 has a structure in which a plurality of disc-shaped members made of PZT are laminated, and when an electric charge is supplied from a signal line 54, it expands in the direction shown by arrow C in the figure and moves the piston 52 in the same direction. As the variable volume chamber 55 is slid in the direction shown in FIG. Since the variable volume chamber 55 is moved, the volume of the variable volume chamber 55 increases. Note that the variable volume chamber 55
When a compressive force in the direction indicated by the arrow in the figure acts on the piezoelectric element 53 as the internal fuel pressure increases, the piezoelectric element 53 transfers an amount of charge to the signal line in accordance with the strain caused by the compressive force. 54.

Incidentally, in the fuel injection pump 3 having the above configuration, the vane pump 23, the cam plate 26, and the plunger 27 rotate as the drive shaft 22 rotates, and the protrusion 26a of the cam plate 26 rides off the cam roller 31 of the roller ring 30. During the lowering process, the plunger 27 moves to the fuel suction stroke and pumps the fuel inside the housing 32 into the pressurizing chamber 34.
, into the communication hole 56 and the inside of the variable capacity chamber 55, while the protrusion 26a of the cam plate 26 is inserted into the roller ring 3.
In the process of riding on the cam roller 31 of 0, the plunger 27
moves to a fuel compression stroke and increases the pressure of the fuel inside the pressurizing chamber 34, the communication hole 56, and the variable capacity chamber 55. Therefore, when the volume of the variable capacity chamber 55 increases, the pressure of the pressurized and force-fed fuel decreases from that during the normal compression stroke.On the other hand, when the volume of the variable capacity chamber 55 decreases, the pressure of the pressurized and force-fed fuel decreases. It rises more than during the normal compression stroke.

A drive circuit 5 for driving the piezoelectric actuator 4 includes a capacitor 61 connected in parallel to a high voltage power source 6, a current-carrying thyristor 62 and a current-carrying coil 63 connected in series between the capacitor 61 and the piezoelectric actuator 4;
A discharge thyristor 64 and a discharge coil 65 connected in parallel to the piezoelectric actuator 4, and the ECU 7 described above.
A trigger pulse is output to the energizing thyristor 62 at the rising edge (ON) of a rectangular signal that is a drive circuit control signal transmitted from
The trigger generator 66 outputs a trigger pulse to the discharge thyristor 64 when the discharge thyristor 64 is turned off.

The drive circuit 5 having the above configuration temporarily stores the high voltage generated by the high voltage power supply 6 in the capacitor 61, and when the energizing thyristor 62 becomes conductive (ON) at the rise of the rectangular signal from the ECU 7, the high voltage is stored in the capacitor 61. On the other hand, when the discharge thyristor 64 becomes conductive (ON) at the fall of the rectangular signal from the ECU 7, the charge stored in the piezoelectric actuator 4 is discharged.

The fuel injection rate control device 1 for the diesel engine includes a drive pulley 21 of the fuel injection pump 3 as a detector.
A reference signal generation sensor 71 detects the fuel injection stroke of each cylinder of the diesel engine 2 when the protrusion 21a approaches.
, a rotational speed sensor 72 that closely faces the pulse gear 24 and detects the rotational speed Ne of the diesel engine 2 from the rotational speed of the drive shaft 22; and a water temperature sensor 7 that detects the cooling water temperature THW of the diesel engine 2.
3. A block temperature sensor 74 that detects a block temperature THE, which is the wall temperature of the cylinder block of the diesel engine 2, and a starter switch 75 that outputs a starter signal when starting the diesel engine 2 are provided.

The ECU 7 mentioned above includes a CPU 7a and a ROM 7b.

It is configured as a logic operation circuit centering around a RAM 7c and a timer 7d, and is connected to a human output section 7f via a common bus 7e to perform human output with the outside. The detection signals of the above-mentioned sensors and switches and the piezoelectric element voltage of the piezoelectric element 53 are input to the CPU 7a via the human output section 7f, and on the other hand,
The CPU 7a outputs a control signal to the drive circuit 5 and the high voltage power supply 6 via the human output section 7f. Note that power is supplied to the drive circuit 5 and the ECU 7 from an on-vehicle battery 76 via an ignition switch 77.

Next, the fuel injection control process executed by the ECU 7 is performed in a third mode.
The injection rate control process will be explained based on the flowchart shown in the figure and the flowchart shown in FIG. 4, respectively. first,
The fuel injection control process will be explained based on the flowchart of FIG. This fuel injection control process is executed in accordance with the human power of the starter signal. First, in step 100,
Initialization processing is performed. In the following step 110, a process of reading the detection signals of each sensor described above is performed. Next, the process proceeds to step 120, where it is determined whether or not the block temperature THB read in step 110 exceeds a predetermined reference block temperature THBO. If the determination is affirmative, the diesel engine 2 is no longer warmed up. The present fuel injection control process is assumed to have been completed, and the fuel injection control process during normal operation is executed. On the other hand, if a negative determination is made, the process proceeds to step 200, assuming that the process is still in a warm-up state. In step 200, which is executed when it is determined that the engine is in the warm-up state, an injection rate control process, which will be described later, is executed, and then the process returns to step 110. Thereafter, in this fuel injection control process, steps 100 to 200 are executed each time the starter signal is input manually.

Next, the injection rate control process executed in step 200 of the fuel injection control process will be explained based on the flowchart of FIG. 4. This injection rate control process is executed when a negative determination is made in step 120 of the fuel injection control process. First, in step 210, a process of reading the piezoelectric element voltage V is performed. In the following step 220, it is determined whether the piezoelectric element voltage V read by the step 210 is equal to or higher than a predetermined control start voltage 70, and if a negative determination is made, the fuel injection which is still in the compression stroke is performed. pump 3
Assuming that the pressure inside the pressurizing chamber 34, that is, the pressure P inside the fuel injection pipe, has not risen sufficiently, step 21 is performed again.
On the other hand, if an affirmative determination is made, it is assumed that the fuel injection pipe internal pressure P has increased to near the fuel injection valve opening pressure PO, and the process proceeds to step 230. Step 23 executed when it is determined that the fuel injection pipe internal pressure P has increased sufficiently
0, a process is performed in which the count value i of a counter that counts the number of intermittent fuel injections performed during one fuel injection period is set to the value 1. In the following step 240, timer 7
A process of resetting and starting d and starting time measurement is performed. Next, the process proceeds to step 250, in which a process is performed in which a drive circuit control signal for supplying charge (ON) Ll and applying voltage Vi to the piezoelectric actuator 4 is output to the drive circuit 5. Through the process of step 250, the piezoelectric actuator 4 is applied with a high voltage Vi calculated based on the count value l of the counter from a predetermined map stored in the ROM 7b, and the piezoelectric element 53 is
expands and reduces the volume of the variable volume chamber 55, so the pressure P inside the fuel injection pipe increases. Then step 260
Then, it is determined whether or not the timer clock value τ exceeds a reference time τi, which is predetermined based on the fuel injection time and calculated according to the count value i of the counter from the map stored in the ROM 7b. If the determination is negative, it is assumed that the fuel injection period is the first of the last one injection period, and the process returns to step 250, and, on the other hand,
If an affirmative determination is made, it is assumed that the first fuel injection period of one injection period has already ended, and the process proceeds to step 270. In step 270, which is executed at the end of the first fuel injection period in one injection period, a process of outputting a drive circuit control signal for discharging (turning off) the charge from the piezoelectric actuator 4 to the drive circuit 5 is carried out. It will be done. Through the process of step 270, the electric charge of the piezoelectric actuator 4 is discharged, the piezoelectric element 53 contracts, and the volume of the variable volume chamber 55 is increased, so that the fuel injection pipe internal pressure P returns to the normal pressure. In the subsequent step 280, a process of adding 1 to the count value i of the counter is performed. Next, the process proceeds to step 290, where the count value i of the counter added in step 280 is stored in the ROM 7b as determined in advance.
Standard number of times 1 calculated from internally stored map
It is determined whether or not the value exceeds 0, and if a negative determination is made, it is assumed that one injection period has not yet ended, and the process returns to step 240. On the other hand, if an affirmative determination is made, one injection period has already ended. Assuming that the injection rate control process has been completed, the present injection rate control process is terminated, and the control proceeds to the fuel injection control process described above.

From then on, this injection rate control process performs steps 210 to 210 every time step 200 is executed in the fuel injection control process.
Execute 290.

Next, an example of the injection rate control described above will be explained with reference to the timing chart of FIG. 5. When the fuel injection pump 3 shifts to the compression stroke, the fuel pressure inside the pressurizing chamber 34, the communication hole 56, and the variable volume chamber 55, that is, the fuel injection pipe internal pressure P starts to rise, and the fuel injection pipe internal pressure P causes the piezoelectric actuator to Since the piezoelectric element 53 inside the piezoelectric element 4 receives a compressive force, the piezoelectric element voltage V rises and becomes equal to or higher than the control start voltage VO at time T1. Therefore, from time T1 to time τ1, high voltage ■1 is applied to the piezoelectric actuator 4.
is applied, the piezoelectric element 53 expands, and the volume of the variable volume chamber 55 decreases. Therefore, the fuel injection pipe internal pressure P rises and exceeds the fuel injection valve opening pressure PO, so the first injection in the main injection period is started with the sufficiently pressurized fuel, and the injection rate increases rapidly. do. When the reference time τ1 has elapsed from the above-mentioned time T1, the first injection in the main fuel injection period ends, and the charge applied to the piezoelectric actuator 4 is discharged, so the piezoelectric element 53 contracts and the variable volume chamber The volume of 55 increases. Therefore, the fuel injection pipe internal pressure P decreases and becomes lower than the fuel injection valve opening pressure PO, so the first injection in the main fuel injection period ends and the injection rate also quickly decreases. Next, high voltage V2 is applied to piezoelectric actuator 4 over time τ2 from time T2, and the second injection in the main fuel injection period is performed. Roughly speaking, high voltage V3 is applied to piezoelectric actuator 4 over time τ3 from time T3, and the third injection, which is the last intermittent fuel injection in the main fuel injection period, is performed. At the end of this third injection, all fuel injections in the main fuel injection period are completed, so the injection rate control process is once completed, and the control shifts to the fuel injection control process described above. Thereafter, while the diesel engine 2 is in a warm-up state, the above-described control is continuously performed.

In this embodiment, the diesel engine 2 is the diesel engine M1, and the fuel injection pump 3 is the fuel injection pump M1.
2, the piezoelectric actuator 4, the drive circuit 5, and the high voltage power supply 6 each correspond to the volume changing means M3. Also, block temperature sensor 74 and ECU? The processing executed by the ECU 7 (steps 110 and 120) is assigned to the warm-up state determining means M4, and the ECU 7 and steps (210 to 290) of the processing executed by the ECU 7 are assigned to the control means M5.

and each function.

As explained above, according to this embodiment, when the block temperature THB of the cylinder block wall surface of the diesel engine 2 in the warm-up state is lower than the reference temperature THBO and fuel spray is likely to adhere to the combustion chamber 14 wall surface, the piezoelectric Since the fuel injection pipe internal pressure P is rapidly increased or decreased by the operation of the actuator 4, from the start time to the end time of fuel injection,
Injection rate control that enables high pressure and intermittent high injection rate fuel injection can be realized.

In this way, by realizing multistage injection due to changes in the injection rate within one injection period of the fuel injected into the diesel engine 2 in a warm-up state, atomization of the fuel spray inside the combustion chamber 14 is promoted. This prevents the injected fuel spray from adhering to the wall surface of the combustion chamber, thereby improving warm-up performance such as shortening warm-up time.

In addition, as combustion progresses rapidly in the warm-up state as described above, the temperature of the combustion chamber of the diesel engine 2 rises, which prevents the moisture and hydrocarbons (HC) in the exhaust from cooling, resulting in white smoke and irritation. Odor emissions can be suppressed.

Furthermore, since combustion occurs smoothly during warm-up,
Since the amount of unburned fuel is reduced, the amount of harmful components such as hydrocarbons (HC) and carbon oxides (CO) contained in the exhaust gas is reduced, and the exhaust purification performance is improved.

In addition, as measures to assist in warming up the diesel engine 2, for example, installation of a heater for heating intake air, fuel injection increase control during warm-up, fuel injection timing advance control during warm-up, and other dedicated warm-up auxiliary devices are installed. Since warm-up performance can be improved with a simple configuration that does not require execution of control processing or control processing, the reliability and durability of the diesel engine fuel injection rate control device 1 can be improved, and the device is easy to implement when mounted on a vehicle. and expands versatility.

Furthermore, in the compression stroke of the fuel injection pump 3, based on the piezoelectric element voltage ■ output from the piezoelectric actuator 4,
Since the piezoelectric actuator 4 is extended by determining that the fuel injection pipe internal pressure P has increased to the vicinity of the fuel injection valve opening pressure PO, accurate and Moreover, it becomes possible to promptly detect the injection start timing, and the control accuracy and responsiveness of injection rate control are improved.

In addition, the piezoelectric actuator 4 is expanded and contracted for a predetermined time τ.
Since this is repeated a predetermined number of times over i, the fuel injection pipe internal pressure P can always be raised to a high pressure at the start of each injection performed multiple times during one injection period.

In this embodiment, the warm-up state is determined based on the block temperature T.
Although the determination was made based on HB, for example, it may be determined that the diesel engine 2 is in a warm-up state when the coolant temperature THW is less than the reference coolant temperature THWO.

Further, for example, the engine may be configured to be determined to be in the warm-up state until after a predetermined period of time has elapsed from the time when the starter signal is input manually and the starting state is completed.

Furthermore, since the piezoelectric actuator 4 is repeatedly expanded and contracted a predetermined number i times over a predetermined time τi, by changing the predetermined time τi and the predetermined number of times 1, the piezoelectric actuator 4 is extended and contracted repeatedly for a predetermined time τi and a predetermined number of times 1. Applicable to injection control.

In this embodiment, the fuel injection pump 3 has been described in which the fuel injection is controlled based on the position of the spill ring. Similar effects can be obtained even when applied to a fuel injection pump that is equipped with a valve and controls fuel injection by opening and closing the overflow valve.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. .

1. Construction As detailed above, the fuel injection rate control device for a diesel engine according to the present invention has a variable volume chamber communicating with a pressurizing chamber of a fuel injection pump when the diesel engine is warmed up. By increasing or decreasing the volume of the diesel engine using a volume changing means to rapidly change the injection rate, and injecting most of the fuel at a high injection rate, the fuel is transferred to the wall surface of the combustion chamber, which has not yet been sufficiently warmed up, of the diesel engine. Constructed to avoid spray adhesion. For this reason, the injection rate of the fuel supplied to the warm-up diesel engine changes rapidly a predetermined number of times during one injection period, and the fuel is injected at a high injection rate and becomes atomized, causing it to flow into the combustion chamber wall. Adhesion of fuel spray is suppressed, so
Smooth combustion and quick completion of the warm-up state can be realized, and the warm-up operation characteristics are dramatically improved, which is an excellent effect.

Furthermore, since combustion proceeds smoothly as described above, the generation of white smoke and irritating odors can be sufficiently suppressed.

Furthermore, since the generation of unburned fuel during warm-up can be prevented, the amount of harmful components such as hydrocarbons (HC) and carbon oxides (CO') contained in the exhaust gas can be reduced, and the exhaust purification performance can also be improved. It increases.

In addition, as a measure to promote warming up of diesel engines, for example,
Warm-up performance can be improved without providing dedicated warm-up auxiliary means, such as intake air heating, increased fuel volume during warm-up, and advance of fuel injection time during warm-up, which simplifies the device configuration and improves device reliability and Durability is also increased, and there are also advantages in that the device's mountability and versatility are expanded.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention, Fig. 2 is a system configuration diagram of an embodiment of the present invention, Fig. 3,
FIG. 4 is a flowchart showing the same control, and FIG. 5 is a timing chart showing the state of the control. Ml... Diesel engine M2... Fuel injection pump M3... Volume changing means M4... Warm-up state determining means M5... Control means 1... Diesel engine fuel injection rate control device 2...・Diesel engine 3...Fuel injection pump 4...Piezoelectric actuator 5...Drive circuit 6...High voltage power supply 7...Electronic Faj unit (ECU) 7a
... CPU 34 ... Pressurization chamber 55 ... Variable volume chamber 72 ... Rotation speed sensor 73 ... Water temperature sensor 74 ... Block temperature sensor 75 ... Starter switch

Claims (1)

[Scope of Claims] 1. A fuel injection pump having a pressurizing chamber for increasing the pressure of fuel supplied to a diesel engine and a variable volume chamber communicating with the pressurizing chamber; a volume changing means for changing the volume according to a command; a warm-up state determining means for determining whether or not the diesel engine is in a warm-up state based on the operating state of the diesel engine; control means for outputting a command to the volume changing means to increase or decrease the volume of the variable volume chamber a predetermined number of times during each fuel injection period of the fuel injection pump when it is determined that the fuel injection pump is in the state; A fuel injection rate control device for a diesel engine featuring: